1. Field of the Invention
This invention generally relates to a cold cathode fluorescent flat lamp, and more particularly to a cold cathode fluorescent flat lamp for separating each group of plasma produced by each electrode pair to prevent cross-talk state.
2. Description of the Related Art
As technology advances, digital devices such as mobile phones, digital cameras, notebook computers, desktop computers are developed to provide multi-functions and easiness to use. For such devices, a display is an indispensable interface for the users to communicate with. Most of such digital devices use LCD panels as their displays in the past years. However, a back light module is required for a LCD panel because the LCD panel itself is not self-emitting.
Since a cold cathode fluorescent flat lamp can provide a good light-emitting efficiency and uniformity, and is a better light source for a larger panel, it had been well applied to the back light modules for LCD panels and other applications. A cold cathode fluorescent flat lamp is a plasma light-emitting device where a high voltage waveform is applied between electrodes to excite the inert gas in the discharge space to high-energy excited molecules, ions, and electrons. Those high-energy excited molecules, ions, and electrons are so-called plasma. The plasma will emit the ultraviolet rays to release the energy and to further excite the fluorescent materials in the cold cathode fluorescent flat lamp, thereby emitting the visible light.
FIG. 1 is a structural view of a conventional cold cathode fluorescent flat lamp. The cold cathode fluorescent flat lamp 100 comprises a first substrate 110, a second substrate 120, a side wall 130, a plurality of electrode pairs 140 (FIG. 1 shows 3 electrode pairs as an example), a fluorescent material 150, and a discharge gas 160. The side wall 130 is disposed at the edge of cold cathode fluorescent flat lamp 100 between the first substrate and the second substrate to form a gas discharge space 170. In addition, a plurality of spacers can be disposed between the substrates to reinforce the structural strength at the central part of the cold cathode fluorescent flat lamp 100.
Referring to FIG. 1, the electrode pair 140 includes an X electrode 140a and a Y electrode 140b. The X electrode 140a and the Y electrode 140b are usually strip electrodes that are disposed in parallel on the first substrate 110. A dielectric layer 180 will usually be disposed on the electrode pair 140 to protect the electrode pair 140 from ion impacts. Further, the discharge gas 160 such as Xe, Ne, Ar, or mixture thereof, is injected into the gas discharge space 170. In addition, the fluorescent material is disposed on the inner wall of the gas discharge space 170 such as the surface of the second substrate 120 or the dielectric layer 180.
The process to turn on the cold cathode fluorescent flat lamp 100 is to apply a high voltage waveform between the X electrode and the Y electrode of the electrode pairs to excite the inert gas to a plasma state. Those excited atoms will emit the ultraviolet rays to release the energy and to further excite the fluorescent material 150 on the inner wall of the gas discharge space 170. However, the electrodes of the conventional cold cathode fluorescent flat lamp are placed in the same gas discharge space. That is, the discharge gas could flow through all the electrodes. During the blink mode, some plasma will flow to a non-emitting area and cause interference so that the individual electrode pair cannot be precisely controlled.